tests: mem_pool: Fixed memory pool test case failure on quark d2000.
tests: mem_pool: Fixed memory pool test case failure on quark d2000.

Due to insufficient ISR stack memory the irq offload was
corrupting the memory.

GH-4766

Signed-off-by: Adithya Baglody <06b44f6fa9a97a2b955c2d2cd070279967447860@intel.com>

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